LED based grow lights may be an option, based on better lumen/watt output as well as generation of waste heat. While its not a Cannabis sp. set up, I replaced the two bulb PCF fixture over my planted aquarium with a single LED based fixture about a year ago and have had great vegetative growth since the swap out (the PDF bulbs were less than 3 months old as swap so little age based lumen fall off out of the PCF tubes).
LEDs can also selected with greater accuracy for the wavelengths of light used by chlorophyll than florescent, metal halide or Na vapor fixtures. When done so the grow environment looks weird and dark to our eyes since there is very little green light, but the plants don't care since they are getting the light THEY want.